The invention relates to heating apparatus the use of which is recommended first of all to meet the heat demand of family homes and individual flats, or a small group of them. Lumpy fuel as used in connection with the invention should be understood to be coal, brown coal, or refined fuel, e.g. briquette and similar materials.
Household heating apparatus is the name of those used to meet the heat demand of individual flats, family homes, or a small group of them. Heat demand means the totality of the heat demand ensuring heating and hot water supply. Accordingly household heating apparatus as used in connection with the invention may be an apparatus similar to stove, or the central boiler of the hot water heating system and other similar apparatuses.
It is generally known, that only those heating apparatuses, used to meet the household heat demand, are suited to the heating technical aspects, in which liquid or gaseous hydrocarbons are burnt. It is a known fact, that the mentioned hydrocarbon types are available for household purpose only in limited quantity. In view of this, the solid lumpy fuels again come into the foreground to meet the household heat demand.
For the continuous operation of the heating apparatuses used for burning lumpy fuels, the feeding of fuel, removal of ash and cinders and automation of the capacity variation are solved only with heating apparatuses of such capacity category, which serve industrial purposes, for instance, with furnaces used for boilers of a power plant. Mechanical grates are used in the industrial furnaces of the mentioned capacity category, such as the chain grates, travelling grates, understokers, overfeed stokers, invert stokers, their various modifications and alternatives. These known furnaces are not applicable in connection with those used for household purposes, hence they did not gain general acceptance in the latter capacity categories. The industrial furnaces are designed generally for a fixed coal type and, consequently, the coal feeding auxiliary plant, the device used for induction and distribution of the air, the device for the removal of ash and cinder, and the automation realizing the functional coordination of the mentioned detail solutions, and designed accordingly.
It is obvious, that in case of the household heating apparatuses no solution will be acceptable, that is suitable for the burning of only one coal type. The lumpy fuels used for household purposes vary not only annually, but even within the same heating season. The households are supplied with coal types of generally poor quality, the dust-content, grain size and moisture content of which vary within wide limits. Occasionally caking, in other cases non-caking cinder type coals are available. Such considerable variations actually require different household apparatuses and often radically different heating technology and fire control.
The most important requirements imposed on the household heating apparatuses are the following:
Effective combustion of fuel and utilization of the heat arising during combustion. No, or only minimal supervision in the process of operation. Continuous heating. In addition to above, the simple construction, inexpensive production and upkeep, furthermore minimal self-consumption are fundamental requirements.
None of the known heating apparatuses used for burning fuels is capable to meet the listed requirements. The known apparatuses generally have vertical grate. The result is that such lumpy cinder piles up on the grate during the process of burning, which can not fall through the gaps even when the grate is stirred. The accumulating cinder represents considerable flow resistance against the combustion air to be induced from underneath, thus flow of the air into the combustion zone necessary for combustion will be uneven during the time of heating. This process will last until the amount of air flowing into the required zone will diminish to such extent, that ignition and combustion can no longer occur. In short, the fire goes out and it can not be restarted until the heating space and grate are cleaned. This process, namely extinction of the fire, is highly dependent on the coal type in connection with the known household heating apparatuses. In case of coal types with caking cinder, the cinder cake forming on the grate renders the combustion in the heating apparatus impossible within a short time. Under such circumstances no effective heating or continuous combustion is conceivable in case of the traditional heating apparatuses. On the other hand these heating apparatuses require relatively a lot of maintenance work and handling activity.
There are so-called slow-combustion stoves, which however are not up to their name referring to continuous operation exactly because of the extremely variable quality and physical condition of the available coal types. These heating apparatuses have not solved either the earlier outlined general problems in the field of household heating apparatuses.